The length, l(T), of a bar depends upon the temperature, T, according to the law where l0 is the length of the bar when T = 0 , and is a positive constant.  (a) Calculate the percentage change in...

The length, l(T), of a bar depends upon the temperature, T, according to the law

where l0 is the length of the bar when T = 0 , and is a positive constant.  (a) Calculate the percentage change in length when T increases from T = 20 to T = 100 , given . (b) Calculate the percentage change in length when T decreases from T = 150 to T = 50 .